Trimethyl borate → tert-butyl-[2-(1H-indol-5-yl)propan-2-yloxy]silane;[1-[(2-methylpropan-2-yl)oxycarbonyl]indol-2-yl]boronic acid

HRID 1061705Notes

Reaction equation

HRID 1061705 reaction equation
[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][C:13]([C:17]([CH3:25])([CH3:24])[O:18][SiH2:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[CH:14][CH:15]=2)[CH:10]=[CH:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].C([N-]C(C)C)(C)C.C[O:34][B:35](OC)[O:36]C>O1CCCC1>[C:20]([SiH2:19][O:18][C:17]([CH3:25])([CH3:24])[C:13]1[CH:12]=[C:11]2[C:16](=[CH:15][CH:14]=1)[NH:8][CH:9]=[CH:10]2)([CH3:23])([CH3:21])[CH3:22].[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[CH:10]=[C:9]1[B:35]([OH:36])[OH:34])=[O:7])([CH3:4])([CH3:3])[CH3:2]

Participants

5

Reactant 3

HCID 8470Trimethyl borateHCID 5062348DiisopropylamideHCID 131722897Tert-butyl 5-(2-tert-butylsilyloxypropan-2-yl)indole-1-carboxylate

Product 1

HCID 157380136tert-butyl-[2-(1H-indol-5-yl)propan-2-yloxy]silane;[1-[(2-methylpropan-2-yl)oxycarbonyl]indol-2-yl]boronic acidYield 95%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

To a stirred solution of 5-(tert-Butyl-dimethyl-silanyloxymethyl)-indole-1-carboxylic acid tert-butyl ester (3-3, 38.6 g, 106.7 mmol) in tetrahydrofuran (400 mL) was slowly added at −78 deg C. a solution of lithiun diisopropylamide in tetrahydrofuran (2M, 80.1 mL, 160.1 mmol, 1.5 equiv). The reaction mixture was stirred at the same temperature for 1 h, treated with trimethylborate, warmed up to ambient temperature, and partitioned between ethyl acetate and 0.5N-HCl. The organic layer was washed with brine, separated, dried (MgSO4) and concentrated in vacuo to give the crude solid. Trituration of the crude product with hexanes followed by filtration and air-drying afforded the desired boronic acid (3-4, 41.3 g, 95%) as a white powder; 1H NMR (400 MHz, CDCl3) δ 7.96 (d, 1H, J=6.8 Hz), 7.54 (s, 1H), 7.47 (s, 1H), 7.32 (d, 1H, J=6.8 Hz), 7.10 (s, 1H), 4.82 (s, 2H), 1.74 (s, 9H), 0.95 (s, 9H), 0.11 (s, 6H).

Workup

  1. custompartitioned between ethyl acetate and 0.5N-HCl
  2. washThe organic layer was washed with brine
  3. customseparated
  4. dry with materialdried (MgSO4)
  5. concentrationconcentrated in vacuo
  6. customto give the crude solid
  7. filtrationTrituration of the crude product with hexanes followed by filtration
  8. customair-drying

Sources & evidence

ORD record
ord-238f8d7627374f47bae6011a92cf50a0
Source dataset
uspto-grants-2005_11
Patent number
US06960590B2

Reaction notes

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